In 2013 Jon took money to tell how he became a gun-toting drug dealer who lived on the streets for more than two years after falling in with gangs as he desperately searched for father figures in Tom’s absence.

Heavily tattooed Jon’s mother Katherine Berkery was 24 when she became pregnant during a three-day fling with then-married Welsh crooner Sir Tom in 1987.

Tom, 78, finally agreed to pay maintenance in 1998 when judge Judith Sheindlin – now known as TV’s Judge Judy – ordered him to take a paternity test.

Even after the test proved Tom was Jon’s dad, the singer – who was renowned for repeatedly cheating on his late wife Linda with hundreds of groupies – only publicly acknowledged his son’s existence in 2008.

Jon appeared to have got clean of drugs attempted to launch a music career in 2013 by gigging around American and promoting himself online on video channels including YouTube.

But his pals now fear for his physical and mental health after a string of tweets from the former drug pusher.

Jon halted all his activities on Twitter in September last year, and last month he was photographed busking for cash in Hoboken, New Jersey, beside a sign that read: “Please help.”

A pal of Jon’s said: “As you can see from his tweets, he’s sadly fallen back into drug taking, wild nights out and poverty.

Jon said in a 2013 interview about how he feels rejection by his dad Tom led to his life of crime and drug abuse: “It all stems back to my dad. I don’t think I realised it for a long time but I was one angry kid, crying out for a father.

“I was four, and could sing all the words to his hit Delilah, when my mother told me who my dad was. She had magazine articles that explained the DNA tests and how my father had tried to smear my mother’s name, claiming he wasn’t responsible for her pregnancy. I was very angry, even then. My anger boiled over at school – I fought every kid and rebelled constantly.”

Jon said he turned to drugs to deal with his feelings for his dad – before he started dealing and carrying guns.

He added: “I tried to numb the pain with drugs – I’ve been smoking weed since I was 16 and I progressed to prescription pills like Oxycontin and Xanax, then ecstasy and cocaine.

But the hitmaker was reminded of the son he snubbed in a 2014 episode of The Voice.

Tattooist Paul Black from South Wales joked with Tom during his audition that he was from New Jersey – adding: “Dad, where have you been all these years? Mam said it was the only way I could get to see you.”

Tom brushed off the gags to his fellow judges as a bit of “Welsh humor”.